CHEMICAL AND ELECTRONIC ASPECTS OF METAL CONJUGATED POLYMER INTERFACES - IMPLICATIONS FOR ELECTRONIC DEVICES

The chemical nature and the electronic structure of metal/conjugated p olymer interfaces are investigated in the context of polymer based lig ht-emitting diodes. We consider the interaction of low-workfunction me tals (Al, Ca) with the surface of conjugated polymers or model oligome r molecules with a combined experimental and theoretical approach. The early stages of the interface formation are followed with X-ray and u ltraviolet photoelectron spectroscopies and the experimental data are compared to the results of quantum chemical calculations. The reaction s of Al and Ca with the organic surface are found to be fundamentally different: while the former forms new covalent bonds onto the polymer backbone, the latter tends to dope the conjugated system. Both types o f reaction are expected to modify drastically the electronic propertie s of the polymer semiconductor.